This invention relates to stick-form anti-perspirant compositions. More particularly, this invention relates to an improved antiperspirant stick composition characterized by superior aesthetic properties and antiperspirant efficacy.
Antiperspirant stick compositions are well known. Conventional anti-perspirant stick compositions are typically composed of a stearate soap-alcohol delivery system and an antiperspirant agent, usually aluminum chlorhydroxy lactate complex. Such antiperspirant sticks are not widely acceptable due to a number of inherent deficiencies, namely lack of efficacy and relatively poor aesthetic properties. It is generally recognized that the alkaline pH of stearate soap-alcohol based stick compositions tends to inactivate aluminum chlorhydroxide, the most effective and commonly used astringent and antiperspirant salt, consequently, there is a considerable reduction in the efficacy when aluminum chlorohydroxide is used in these compositions. In addition, soap-alcohol based stick compositions exhibit considerable drag on the skin during application and also leave a moist, tacky residue on the skin after application.
Because of the relatively low efficacy of traditional soap-alcohol based stick compositions, the toiletries industry has vigorously explored more effective alternative delivery systems. One typical system is composed of a wax-like matrix which serves as a carrier for aluminum chlorhydroxide and a volatile silicone composition. In the majority of the stick compositions presently on the market, stearyl alcohol is used as the support matrix and assorted cyclic dimethyl siloxane compounds are used as the volatile silicone component. While these more modern antiperspirant stick compositions are more effective as antiperspirants and leave a fairly dry residue on application to the skin, they also have a number of inherent deficiencies. These stick compositions tend to drag during application and are lacking in internal cohesion, dimensional stability and homogeneity. In addition, these stick compositions do not include water-soluble components to assist in activating the aluminum chlorhydroxide salts in the presence of perspiration and they exhibit a whitening effect produced by a powdery residue remaining on the skin after application. After storage at 40.degree. C. for 24 hours they exhibit even greater distortion, lack of internal cohesion and drag on the skin.
It is, therefore, an object of this invention to provide an effective, inert, non-irritating, non-tacky and cosmetically attractive antiperspirant stick composition that also exhibits improved internal cohesion homogeneity, dimensional stability, ease of application and generally improved aesthetic properties together with a high order of astringent and antiperspirant efficacy. Another object of this invention is to provide an improved delivery system that permits the active astringent and antiperspirant salt to be delivered on to the skin without dimunition in antiperspirant activity. Other objects and advantages will become readily apparent from the following description and appended claims.